1. Field of the Invention
This invention relates to a nail-driving gun barrel assembly with a safe and robust cartridge ejection mechanism, more particular to a nail-driving gun barrel assembly including a barrel and an ejector having a cylindrical block sleeved coaxially and slidably on a firing end portion of the barrel for ejecting an exhaust explosive cartridge.
2. Description of the Related Art
Referring to FIGS. 1 to 2, U.S. Pat. No. 3,643,850 discloses a pin-driving tool that includes a barrel 12 having a rear part 121, an action housing 13 fitted slidably to the rear part 121 and carrying a breech block 14, and an L-shaped ejector 15 mounted to the rear part 121 and slidable relative to the rear part 121 between first and second axial positions (see FIGS. 1 and 2). The rear part 121 has a cutout surface 120, and is formed with a powder chamber 122 for receiving an explosive cartridge 10, a bottom slot 123, and a cutout recess 124. The L-shaped ejector 15 has an insertion section 151 which is inserted fittingly and movably in the bottom slot 123, and an ejecting section 152. The ejecting section 152 is received in the cutout recess 124, and mates the cutout surface 120 to define a stepped bore 1220 for accommodating the explosive cartridge 10 when the L-shaped ejector 15 is disposed at the first axial position. A pawl screw element 16 is secured to the active housing 13. The insertion section 152 is provided with a projection 17 that protrudes therefrom. After firing the explosive cartridge 10, the barrel 12 is moved frontwardly relative to the action housing 13 and the pawl screw element 16, so that the projection 17 is brought into contact with the pawl screw element 16 to move the L-shaped ejector 15 from the first axial position to the second axial position for ejecting the exhausted explosive cartridge 10.
An upper clearance (not shown) is formed between a downward-facing portion of the cutout surface 120 and a top end of the ejecting section 152 when the L-shaped ejector 15 is disposed at the first axial position. For safety, low noise and pin-driving efficiency reasons and for preventing explosive residue from entering the clearance and the action housing 13, the upper clearance should be as narrow as possible so as to reduce risks to safety, noise, and amounts of an explosion gas and the explosive residue escaping from the stepped bore 1220 and the powder chamber 122 through the clearance into the action housing 13. However, the configuration and arrangement of the L-shaped ejector 15 have a tendency to result in difficulty in controlling tolerances of the L-shaped ejector 15 in connection with tolerances of the rear part 121 of the barrel 12 during manufacturing or machining of the barrel 12 and the L-shaped ejector 15, which, in turn, may result in a relatively large clearance between the downward-facing portion of the cutout surface 120 and the top end of the ejecting section 152 of the L-shaped ejector 15.
Moreover, the explosion of the explosive cartridge 10 may result in fast recoil movement of the L-shape ejector 15, which can result in a strong impact between the projection 17 and the rear part 121, which, in turn, results in deformation of the projection 17.